Renewable green energy sources such as photovoltaic or solar cells are gaining more importance. There is a growing demand for clean sources of energy. Such photovoltaic cells harvest energy light during the day and are idle at night. They can be combined with solar concentrators or they can be exposed directly to sunlight. A good place to position such solar panels is the front surface of a building facing the south or on the ground. However, at night, because there is less light available and light absorption of the solar cells is high, such a building covered with solar panels look very dark so that other illumination is required to provide orientation and improve appearance.
Furthermore, the principle of a Luminescent Solar Concentrator (LSC) is described in WO2006/088369 A2, for example, and is shown schematically in FIG. 2. It is based on a transparent (polymer or glass) matrix or plate 30 containing luminophores 40, such as fluorescent dyes. (Solar) radiation is absorbed by the luminophores 40 and reemitted in all directions. Apart from fluorescent dyes, semiconductor nanocrystals such as quantum dots or quantum rods, or phosphors can be used as the luminophores 40. Due to internal reflection within the polymer or glass plate 30, most of the reemitted light is guided to the sides of the plate 30, where solar cells 20 can be attached. Thus, only a small effective area of the solar cells 20 is required for a relatively large area that collects the sun, making the device economically favourable.
So far, the LSCs are designed to be a low-cost and large-area solar cell. The intrinsic color and variation thereof make them promising building blocks for integration in e.g. buildings. However, the efficiency of the state-of-the-art LSCs in not sufficient to compete with conventional silicon solar cells, and large-scale production of LSCs as alternative energy source is far away. Another potential market for LSCs is therefore as “decorative” power supply in smaller (consumer) products.